An antimony-free nonwoven substrate with high liquid holding rate and a facial mask containing the same

Abstract

The present invention relates to an antimony-free nonwoven substrate with high liquid retention rate. The substrate is a three-layer composite structure, which is formed by carding hyperbranched modified polyester fibers, adhesive fibers and natural cellulose fibers into a web and then waterjet reinforced and compounded. The hyperbranched modified polyester fibers are obtained by prepolymerization and polycondensation of terephthalic acid, C2-5 diol and hyperbranched polyol, and no antimony-containing catalyst is used in the preparation process. By adding hyperbranched polyol in both the prepolymerization and polycondensation stages of polyester fiber preparation, the present invention constructs a novel unidirectional water-conducting multi-layer structure. The upper polyester fiber layer forms a polyester fiber layer with a cross-linked network structure due to the addition of hyperbranched polyol, which has a high degree of compactness, can naturally form a humidity gradient to achieve the purpose of water retention, and will not reduce the liquid retention rate. Moreover, it has good water retention property and can keep water from flowing out within 1 hour under normal conditions.

Description

Technical Field

[0001] The present invention belongs to the technical field of non-woven fabrics, and particularly relates to an antimony-free non-woven substrate with high liquid holding rate and a facial mask containing the same. Background Art

[0002] Patch-type facial masks are fast-moving consumer products in the beauty market and occupy a large share of the facial mask market. Currently, the carriers of patch-type facial masks are mainly non-woven material facial mask substrates, mainly spunlace non-woven materials. The fiber raw materials used are mainly natural cellulose fibers and regenerated cellulose fibers. With the continuous improvement of consumers' requirements for facial mask types, the facial mask substrates are also constantly updated and changed, and their production processes and raw materials used are constantly innovated and developed. Therefore, studying the spunlace facial mask substrates prepared from polyester fibers and their properties is beneficial to the development of diversified products of facial mask substrates and provides consumers with richer choices.

[0003] Currently, for polyester fiber materials based on polyester materials, during synthesis, antimony-containing catalysts are added, such as antimony trioxide, antimony acetate, etc. Even when the concentration of antimony is reduced to 10 -4 to 10 -5 , it still has strong toxicity. Moreover, most of the antimony-containing catalysts will remain in the polyester fibers. Antimony dissolves and binds to red blood cells. Especially trivalent antimony, its toxicity is about 10 times that of pentavalent antimony. Antimony-containing textiles, if used for next-to-skin fabrics and are in frequent contact with the human skin, will transfer into the body and continuously accumulate. Therefore, in the field of patch-type facial masks, antimony-free polyester fibers are required, which are biocompatible and environmentally friendly. Also, the softness, water absorption, liquid holding capacity, and breathability of non-woven spunlace fabrics based on polyester need to be considered.

[0004] CN112176525A discloses a unidirectional water-conducting facial mask substrate, which is a three-layer composite structure. The upper layer is a hydrophobic modified polyester fiber, the middle layer is a chitosan-modified polyvinyl alcohol fiber, and the lower layer is an adhesive fiber. The hydrophobic modified polyester fiber is obtained by pre-polymerization and polycondensation of terephthalic acid, butanediol, and castor oil-modified polyol. The catalyst still uses antimony trioxide, and the residual trivalent antimony poses a safety hazard, especially when used as a facial mask substrate in long-term contact with the human skin. In addition, when the surface density of the hydrophobic modified polyester fiber in this patent needs to be relatively large to effectively achieve the purpose of unidirectional water conduction, although the use of hydrophobic polyester fiber will significantly improve the water retention, the liquid holding rate will decrease to a certain extent, and it is not very comfortable to use.

[0005] CN110053317A discloses a composite spunlace non-woven mask base fabric with fast moisture conduction, which includes upper, middle and lower layers. A layer of perforated PE film is arranged between the middle layer and the lower layer. The upper layer and the middle layer are bonded by spunlace and perforated to form a fast moisture conduction layer. The lower layer is a composite spunlace fabric of honeysuckle fiber and xylitol fiber, serving as the base layer of the base fabric, and is compounded with the moisture conduction layer through hot air bonding. Due to the loose entanglement of the adhesive fibers and the tight entanglement of the ultra-fine fibers, the equivalent radius gap between the two capillaries becomes larger, the differential capillary effect is significant, and there is a good moisture conduction gradient (i.e., unidirectional water conduction ability), which improves the absorption rate of the nutrient solution and has a high liquid holding rate.

[0006] However, for the technologies of the above patents, although they all adopt a certain degree of unidirectional water conduction to improve the liquid holding rate and water retention. But the test of water retention, especially in the previous patent 112176525A, the test method is not scientific enough. It measures the change of the liquid holding rate of the mask substrate under the conditions of 25°C and RH60%, which can only reflect that the liquid holding rate of the mask substrate changes little with time, but cannot truly reflect the loss of the mask nutrient solution at room temperature and conventional humidity after absorbing the mask nutrient solution. In addition, if the water repellency of the hydrophobic layer is increased to improve the water retention performance, it will have an adverse effect on the air permeability of the mask, and it will also bring discomfort and a bad feeling of poor air permeability to the mask users. Therefore, it is necessary to develop a non-woven substrate for masks with excellent comprehensive performance, high liquid holding rate, good water retention, and good air permeability and transparency. Summary of the Invention

[0007] In order to solve the shortcomings that the composite performance of the mask substrate based on polyester fiber in the prior art is not excellent enough and cannot have both high liquid holding rate, moisture retention, air permeability and comfort, the present invention proposes an antimony-free non-woven substrate with high liquid holding rate and its preparation method, as well as a mask containing this substrate. The present invention realizes the above object through the following technical solutions:

[0008] An antimony-free non-woven substrate with high liquid holding rate, which is a three-layer composite structure, is formed by carding and web-forming of hyperbranched modified polyester fiber, adhesive fiber and natural cellulose fiber, and then reinforced and compounded by spunlace; the hyperbranched modified polyester fiber is obtained by prepolymerization and polycondensation of terephthalic acid, C2-5 diol and hyperbranched polyol, and no antimony-containing catalyst is used in the preparation process.

[0009] The C2-5 diol is selected from at least one of ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, and neopentyl glycol.

[0010] The antimony-free high liquid-holding nonwoven substrate with a three-layer composite structure of the present invention has a hyperbranched modified polyester fiber layer on the upper layer, an adhesive fiber layer in the middle layer, and natural cellulose fibers on the lower layer. The uppermost layer is relatively rough and dense hyperbranched modified polyester fibers, the middle layer is an adhesive fiber layer with strong water absorption, which is convenient for forming a unidirectional water conduction structure, and the lowermost layer is a natural cellulose fiber layer, which is biocompatible and has no side effects after long-term contact.

[0011] The natural cellulose fibers are selected from at least one of hemp fibers, cotton fibers, and bamboo pulp fibers. The dry strength of the adhesive fibers is 35-50 cN / tex.

[0012] Furthermore, the fineness of the hyperbranched modified polyester fibers is 1.0-1.2 dtex, and the surface density after carding of the hyperbranched modified polyester fibers is 10-15 g / m 3 ; the fineness of the natural cellulose fibers is 0.6-0.9 dtex, and the surface density after carding of the natural cellulose fibers is 20-30 g / m 3 ; the fineness of the adhesive fibers is 1.2-1.4 dtex, and the surface density after carding of the adhesive fibers is 10-15 g / m 3 .

[0013] Furthermore, the hyperbranched modified polyester fibers are prepared by a preparation method including the following steps:

[0014] (S1) Under an inert atmosphere, trimethylolpropane, sorbitol, dimethylolpropionic acid, and p-toluenesulfonic acid are fed in a molar ratio of 7-10:1-1.4:25-30:0.3-1, and the molar ratio of the carboxyl group in dimethylolpropionic acid to the hydroxyl groups in trimethylolpropane and sorbitol is 1.05-1.15:1; an esterification reaction is carried out to obtain a first-generation branched polyol; dimethylolpropionic acid and p-toluenesulfonic acid are added to the first-generation branched polyol, and the addition amount of dimethylolpropionic acid is such that the molar ratio of the carboxyl group of dimethylolpropionic acid to the hydroxyl group of the branched polyol is 1-1.03:1, and the addition amount of p-toluenesulfonic acid is 0.01-0.03 times the molar amount of dimethylolpropionic acid, and the esterification reaction is continued to obtain a second-generation branched polyol; the above operation is repeated (continuing to add the carboxyl group of dimethylolpropionic acid and p-toluenesulfonic acid, and the addition amount of dimethylolpropionic acid is such that the molar ratio of the carboxyl group of dimethylolpropionic acid to the hydroxyl group of the branched polyol is 1-1.03:1, and the addition amount of p-toluenesulfonic acid is 0.01-0.03 times the molar amount of dimethylolpropionic acid) to obtain a third-generation hyperbranched polyol or a fourth-generation hyperbranched polyol;

[0015] In theory, further adding dimethylolpropionic acid for esterification reaction to obtain fifth-generation or even higher-generation hyperbranched polyols will further improve the unidirectional water conduction ability of the facial mask substrate. However, it is found in actual operation that when preparing fifth-generation hyperbranched polyols, the solubility of the product in acetone becomes poor, which is not convenient for production; moreover, when the obtained fifth-generation hyperbranched polyols are used in the manufacture of hyperbranched modified polyester fibers, the performance of the obtained facial mask substrate is not further improved. Therefore, in the present invention, hyperbranched polyols are preferably third-generation hyperbranched polyols or fourth-generation hyperbranched polyols.

[0016] (S2) Terephthalic acid and C2-5 diol are fed in a molar ratio of 1.05-1.14:1, and then 5-8 wt% of the third-generation or fourth-generation hyperbranched polyol prepared in step (S1) based on the mass of terephthalic acid is added. First, pre-polymerization is carried out at 210-230 °C and a pressure of 0.6-0.9 MPa for 1-2 h; then, 10-15 wt% of the third-generation or fourth-generation hyperbranched polyol prepared in step (S1) based on the mass of terephthalic acid and an organotin catalyst are added for polycondensation. The polycondensation reaction temperature is 250-270 °C, the pressure is 0.01-0.05 MPa, and the polycondensation is carried out until the acid value of the system is lower than 10 mg KOH / g. Generally, the polycondensation time is 4-6 h; the addition amount of the organotin catalyst is 1-2 wt% of the mass of terephthalic acid; cool, filter, cast into strips, and pelletize to obtain polyester chips;

[0017] (S3) The polyester chips, polyvinyl alcohol, lubricant, antibacterial agent, and antioxidant are fed into a twin-screw extruder according to a mass ratio of 100:5-8:0.5-2:0.5-2:0-1, and extruded and pelletized;

[0018] (S4) The masterbatch obtained in step (S3) is melt-spun, cooled, drawn, and wound to obtain hyperbranched modified polyester fibers.

[0019] Further, in step (S1), the conditions of the esterification reaction are to control the reaction temperature at 120-140 °C and react for 4-6 h; the post-treatment after the esterification reaction is cooling, rotary evaporation. The obtained product is dissolved in acetone, a non-polar solvent is added, precipitation occurs, filtration is carried out, and drying is carried out; the non-polar solvent is selected from at least one of n-hexane and petroleum ether.

[0020] The inventor unexpectedly found that in step (S2), under the preparation process conditions where the hyperbranched polyol is added in two stages in the pre-polymerization and polycondensation stages, and the addition amount is less during pre-polymerization and more during polycondensation, the obtained facial mask substrate can simultaneously meet the water retention, liquid holding rate, and optimal mechanical properties. Although the reason is unknown, if the same mass of hyperbranched polyol is added only in the pre-polymerization stage or only in the polycondensation stage, or the addition amount in the polycondensation stage is more and the addition amount in the pre-polymerization stage is less, the comprehensive excellent effect cannot be achieved.

[0021] Further, in step (S2), the organotin catalyst is selected from at least one of dibutyltin dilaurate, tin oxalate, stannous octoate, and dibutyltin dioctoate. The present invention does not use an antimony-based catalyst, avoiding the health risks caused by antimony.

[0022] Further, in step (S3), the number-average molecular weight of the polyvinyl alcohol is 1000 - 2000 g / mol. There are no particular limitations on the lubricant, antibacterial agent, and antioxidant, and those conventional in the art can be used. For example, the lubricant is selected from pentaerythritol stearate and polyvinylpyrrolidone; the antibacterial agent is selected from at least one of nano silver and quaternary ammonium salts; the antioxidant is selected from at least one of BHT1010 and 2246. The process of twin-screw extrusion is well-known in the art, and the working temperature is 190 - 230 °C. For example, there are 6 working zones, the first zone is 190 °C, the second zone is 200 °C, the third zone is 210 °C, the fourth zone is 220 °C, the fifth zone is 230 °C, and the sixth zone is 220 °C.

[0023] In step (S4), the temperature of the melt spinning process is 300 - 320 °C, the setting temperature is 140 - 160 °C, the POY spinning speed is 2500 - 3000 m / min, the POY draw ratio is 1.5 - 2 times, the FDY spinning speed is 4000 - 4500 m / min, the FDY draw ratio is 3 - 3.5 times, and the winding speed is 2000 - 3000 r / min.

[0024] The present invention also provides a method for preparing the antimony-free nonwoven substrate with high liquid holding rate, comprising the following steps:

[0025] Loosen the hyperbranched modified polyester fiber, adhesive fiber, and natural cellulose fiber respectively, card them into webs, and laminate the hyperbranched modified polyester fiber web, adhesive fiber web, and natural cellulose fiber web in sequence from top to bottom. After lamination, hydroentangle and dry, and then crimp to obtain the antimony-free nonwoven substrate with high liquid holding rate.

[0026] Further, control the injection amount of each fiber to meet the requirement of the basis weight, that is, the basis weight of the hyperbranched modified polyester fiber after carding is 10 - 15 g / m 3 ; the basis weight of the natural cellulose fiber after carding is 20 - 30 g / m 3 ; the basis weight of the adhesive fiber after carding is 10 - 15 g / m 3 .

[0027] Further, the composite is a 30 - 60° composite, such as a 45° composite; the hydroentangling reinforcement process is well-known in the art. The action distance of the water needle is 10 - 20 mm, such as 14 mm; 3 - 5 passes of hydroentangling reinforcement are carried out, and the water pressure is 1.5 - 8 MPa, and the water pressure first rises and then falls. For example, in a specific embodiment of the present invention, it is a 4-pass hydroentangling reinforcement process. The water pressure of the first pass of hydroentangling is 1.5 - 3 MPa, the water pressure of the second pass of hydroentangling is 3 - 6 MPa, the water pressure of the third pass of hydroentangling is 6 - 8 MPa, and the water pressure of the fourth pass of hydroentangling is 3 - 5 MPa.

[0028] The present invention also provides a facial mask, which includes a facial mask substrate and a nutrient solution, and the facial mask substrate is the above-mentioned antimony-free high liquid-holding nonwoven substrate.

[0029] The excellent effects of the present invention are as follows: Instead of constructing a unidirectional water-conducting nonwoven substrate by utilizing the different hydrophilic and hydrophobic abilities between layers in a conventional multi-layer structure, a novel unidirectional water-conducting multi-layer structure is constructed by adding hyperbranched polyol in the prepolymerization and polycondensation steps of preparing polyester fibers. Through the addition of hyperbranched polyol, the upper polyester fiber layer forms a polyester fiber layer with a cross-linked network structure, which has a high degree of compactness, can naturally form a humidity gradient to achieve the purpose of water retention, and will not reduce the liquid-holding rate; under normal conditions, the water can be kept from flowing out within 1 hour. Specific Embodiment

[0030] To make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be described in detail below. The following embodiments are convenient for better understanding of the present invention, but do not limit the present invention. The experimental methods in the following embodiments are all conventional methods unless otherwise specified.

[0031] The test of the hydroxyl content of the branched polyol is obtained by using phthalic anhydride as an acylating reagent for testing.

[0032] Preparation Example 1

[0033] (S1) Under a nitrogen atmosphere, trimethylolpropane, sorbitol, dimethylolpropionic acid, and p-toluenesulfonic acid are fed in a molar ratio of 10:1:25:0.7, and the molar ratio of the carboxyl group in dimethylolpropionic acid to the hydroxyl groups in trimethylolpropane and sorbitol is 1.1:1. An esterification reaction is carried out at 120 °C for 5 h. After the reaction is completed, it is cooled, rotary evaporated, the product is dissolved in acetone, petroleum ether is added, a precipitate is precipitated, filtered, and dried to obtain a first-generation branched polyol. Dimethylolpropionic acid and p-toluenesulfonic acid are continuously added to the first-generation branched polyol for esterification reaction. The addition amount of dimethylolpropionic acid satisfies that the molar ratio of the carboxyl group of dimethylolpropionic acid to the hydroxyl group of the branched polyol is 1.03:1, and the addition amount of p-toluenesulfonic acid is 0.03 times the molar amount of dimethylolpropionic acid. The esterification reaction is continued. After the reaction is completed, it is cooled, rotary evaporated, the product is dissolved in acetone, petroleum ether is added, a precipitate is precipitated, filtered, and dried to obtain a second-generation branched polyol. Dimethylolpropionic acid and p-toluenesulfonic acid are continuously added to the second-generation branched polyol for esterification reaction. The addition amount of dimethylolpropionic acid satisfies that the molar ratio of the carboxyl group of dimethylolpropionic acid to the hydroxyl group of the second-generation branched polyol is 1.03:1, and the addition amount of p-toluenesulfonic acid is 0.03 times the molar amount of dimethylolpropionic acid. The esterification reaction is continued. After the reaction is completed, it is cooled, rotary evaporated, the product is dissolved in acetone, petroleum ether is added, a precipitate is precipitated, filtered, and dried to obtain a third-generation hyperbranched polyol. Dimethylolpropionic acid and p-toluenesulfonic acid are continuously added to the third-generation branched polyol for esterification reaction. The addition amount of dimethylolpropionic acid satisfies that the molar ratio of the carboxyl group of dimethylolpropionic acid to the hydroxyl group of the third-generation branched polyol is 1.03:1, and the addition amount of p-toluenesulfonic acid is 0.03 times the molar amount of dimethylolpropionic acid. The esterification reaction is continued. After the reaction is completed, it is cooled, rotary evaporated, the product is dissolved in acetone, petroleum ether is added, a precipitate is precipitated, filtered, and dried to obtain a fourth-generation hyperbranched polyol;

[0034] (S2) Terephthalic acid and ethylene glycol are fed in a molar ratio of 1.1:1, and 8 wt% of the fourth-generation hyperbranched polyol prepared in step (S1) based on the mass of terephthalic acid is added. First, it is prepolymerized at 210 °C and a pressure of 0.6 MPa for 1 h. Then, 10 wt% of the fourth-generation hyperbranched polyol prepared in step (S1) based on the mass of terephthalic acid and dibutyltin dilaurate are added for polycondensation. The addition amount of dibutyltin dilaurate is 1 wt% of the mass of terephthalic acid. The polycondensation reaction temperature is 260 °C and the pressure is 0.05 MPa. The polycondensation is carried out until the acid value of the system is lower than 10 mg KOH / g. It is cooled, filtered, pelletized, and cut into polyester chips;

[0035] (S3) Polyester chips, polyvinyl alcohol (number-average molecular weight 2000 g / mol), lubricant pentaerythritol stearate, antibacterial agent nano-silver, and antioxidant BHT1010 are fed into a twin-screw extruder (6 working zones, zone 1 at 190 °C, zone 2 at 200 °C, zone 3 at 210 °C, zone 4 at 220 °C, zone 5 at 230 °C, zone 6 at 220 °C) according to a mass ratio of 100:5:1:1:0.5, and then extrusion granulation is carried out;

[0036] (S4) The masterbatch obtained in step (S3) is melt-spun, cooled, drawn and wound to obtain hyperbranched modified polyester fibers; the process temperature of melt spinning is 300 °C, the setting temperature is 150 °C, the spinning speed of POY is 2500 m / min, the draw ratio of POY is 1.5 times, the spinning speed of FDY is 4000 m / min, the draw ratio of FDY is 3 times, and the winding speed is 3000 r / min.

[0037] Preparation Example 2

[0038] Other conditions and operations are the same as those in Preparation Example 1, except that step (S1) is changed to:

[0039] Under a nitrogen atmosphere, trimethylolpropane, sorbitol, dimethylolpropionic acid, and p-toluenesulfonic acid are fed according to a molar ratio of 10:1:25:0.7, and the molar ratio of the carboxyl group in dimethylolpropionic acid to the hydroxyl groups in trimethylolpropane and sorbitol is 1.1:1; an esterification reaction is carried out at 120 °C for 5 h. After the reaction is completed, it is cooled, rotary evaporated, the product is dissolved in acetone, petroleum ether is added, a precipitate is precipitated, filtered, and dried to obtain first-generation branched polyol; dimethylolpropionic acid and p-toluenesulfonic acid are continuously added to the first-generation branched polyol for esterification reaction. The added amount of dimethylolpropionic acid satisfies that the molar ratio of the carboxyl group of dimethylolpropionic acid to the hydroxyl group of the branched polyol is 1.03:1, and the added amount of p-toluenesulfonic acid is 0.03 times the molar amount of dimethylolpropionic acid. The esterification reaction is continued. After the reaction is completed, it is cooled, rotary evaporated, the product is dissolved in acetone, petroleum ether is added, a precipitate is precipitated, filtered, and dried to obtain second-generation branched polyol; dimethylolpropionic acid and p-toluenesulfonic acid are continuously added to the second-generation branched polyol for esterification reaction. The added amount of dimethylolpropionic acid satisfies that the molar ratio of the carboxyl group of dimethylolpropionic acid to the hydroxyl group of the second-generation branched polyol is 1.03:1, and the added amount of p-toluenesulfonic acid is 0.03 times the molar amount of dimethylolpropionic acid. The esterification reaction is continued. After the reaction is completed, it is cooled, rotary evaporated, the product is dissolved in acetone, petroleum ether is added, a precipitate is precipitated, filtered, and dried to obtain third-generation hyperbranched polyol;

[0040] Step (S2) is changed to:

[0041] (S2) Terephthalic acid and 1,4-butanediol are fed in a molar ratio of 1.1:1, and then 5 wt% of the third-generation hyperbranched polyol prepared in step (S1) based on the mass of terephthalic acid is added. First, pre-polymerization is carried out at 210 °C and a pressure of 0.6 MPa for 1 h; then 15 wt% of the third-generation hyperbranched polyol prepared in step (S1) based on the mass of terephthalic acid and dibutyltin dilaurate are added for polycondensation. The addition amount of dibutyltin dilaurate is 1 wt% of the mass of terephthalic acid. The polycondensation reaction temperature is 260 °C, the pressure is 0.05 MPa, and polycondensation is carried out until the acid value of the system is lower than 10 mg KOH / g. Then it is cooled, filtered, strip-cast, and pelletized to obtain polyester chips.

[0042] Preparation Example 3

[0043] Other conditions and operations are the same as those in Preparation Example 1, except that step (S2) is changed to:

[0044] Terephthalic acid and ethylene glycol are fed in a molar ratio of 1.1:1, and then 18 wt% of the fourth-generation hyperbranched polyol prepared in step (S1) based on the mass of terephthalic acid is added. First, pre-polymerization is carried out at 210 °C and a pressure of 0.6 MPa for 1 h; then polycondensation is carried out by adding 1 wt% of dibutyltin dilaurate based on the mass of terephthalic acid. The polycondensation reaction temperature is 260 °C, the pressure is 0.05 MPa, and polycondensation is carried out until the acid value of the system is lower than 10 mg KOH / g. Then it is cooled, filtered, strip-cast, and pelletized to obtain polyester chips.

[0045] That is, in step (S2), all of the fourth-generation hyperbranched polyol is added in the pre-polymerization stage.

[0046] Preparation Example 4

[0047] Other conditions and operations are the same as those in Preparation Example 1, except that step (S2) is changed to:

[0048] Terephthalic acid and ethylene glycol are fed in a molar ratio of 1.1:1. First, pre-polymerization is carried out at 210 °C and a pressure of 0.6 MPa for 1 h; then 18 wt% of the fourth-generation hyperbranched polyol prepared in step (S1) based on the mass of terephthalic acid and 1 wt% of dibutyltin dilaurate based on the mass of terephthalic acid are added for polycondensation. The polycondensation reaction temperature is 260 °C, the pressure is 0.05 MPa, and polycondensation is carried out until the acid value of the system is lower than 10 mg KOH / g. Then it is cooled, filtered, strip-cast, and pelletized to obtain polyester chips.

[0049] That is, in step (S2), all of the fourth-generation hyperbranched polyol is added in the polycondensation stage.

[0050] Comparative Preparation Example 1

[0051] Other conditions and operations are the same as those in Preparation Example 1, except that the preparation of the hyperbranched polyol in step (S1) is not carried out, and no hyperbranched polyol is added in step (S2). That is, it is carried out according to the ordinary polyester fiber production process.

[0052] Example 1

[0053] The hyperbranched modified polyester fiber (fineness 1.0 dtex), the viscose fiber (dry strength 45 cN / tex, fineness 1.2 dtex) and the hemp fiber (fineness 0.7 dtex) prepared in Preparation Example 1 were respectively opened and carded into a web, and the injection amounts of the respective fibers were controlled so that the areal density of the hyperbranched modified polyester fiber after being carded into a web was 15 g / m 3 and the areal density of the viscose fiber after being carded into a web was 30 g / m 3 , and the areal density of the hemp fiber after being carded into a web was 15 g / m 3 . The hyperbranched modified polyester fiber web, the viscose fiber web and the natural cellulose fiber web were compounded at 45° in sequence from top to bottom, and after compounding, hydroentangling reinforcement was carried out. The conditions for hydroentangling reinforcement were: the water needle action distance was 14 mm, and 4 passes of hydroentangling reinforcement were carried out. The water pressure of the first pass of hydroentangling was 2 MPa, the water pressure of the second pass of hydroentangling was 5 MPa, the water pressure of the third pass of hydroentangling was 8 MPa, and the water pressure of the fourth pass of hydroentangling was 3 MPa; after hydroentangling reinforcement, it was dried and crimped to obtain an antimony-free nonwoven substrate with a high liquid holding rate.

[0054] Example 2

[0055] Other conditions and operations are the same as those in Example 1, except that the hyperbranched modified polyester fiber was prepared in Preparation Example 2.

[0056] Example 3

[0057] Other conditions and operations are the same as those in Example 1, except that the hyperbranched modified polyester fiber was prepared in Preparation Example 3.

[0058] Example 4

[0059] Other conditions and operations are the same as those in Example 1, except that the hyperbranched modified polyester fiber was prepared in Preparation Example 4.

[0060] Comparative Example 1

[0061] Other conditions and operations are the same as those in Example 1, except that the hyperbranched modified polyester fiber was replaced by the polyester fiber prepared in Comparative Preparation Example 1.

[0062] Effect Example

[0063] Referring to Part 3 of GB / T 24218.3-2010, the breaking strength of the facial mask substrate in the wet state was tested using a YG028-500 type tensile tester. The facial mask substrate was immersed in distilled water for 10 min to fully absorb water and then taken out, and its mechanical properties were immediately tested. The size of the facial mask substrate was cut into 50 mm × 200 mm, the clamping distance was set at 100 mm, the stretching speed was 100 mm / min, and the stretching experiment was carried out in an equal-speed stretching manner.

[0064] Referring to the determination of absorbency in GB / T 24218.6-2010, the water absorbency and water retention of the facial mask substrates of the examples and comparative examples of the present invention were tested. The facial mask substrates were cut into 10 cm × 10 cm. The water absorbency is expressed by the liquid absorption amount S (g / g), S0 = (m1 - m0) / m0, where m1 represents the mass of the facial mask substrate after being taken out after being immersed in distilled water for 10 min, hanging the sample vertically on a metal copper mesh, and standing for 1 min to drain off the excess water, m0 represents the mass of the facial mask substrate before immersion in water, and S0 represents the maximum amount of water that can be absorbed by the facial mask substrate per unit mass. The liquid absorption amount of the facial mask substrate is an important index for considering the facial mask material, directly affecting the amount of essence absorbed by the facial mask, and is an important guarantee for the skin to absorb nutrients.

[0065] The water retention property is to test the weight loss rate of the facial mask over time under the state of saturated liquid holding at regular intervals under the environmental temperature of 25 °C, relative humidity of 60%, and standard atmospheric pressure environment. The lower the weight loss rate, the better the water retention property.

[0066] GB / T 24218-2018 - Nonwoven fabric air permeability test standard. Using a YG461E type full-automatic fabric air permeability tester, the air permeability of the facial mask substrate in the dry state was tested.

[0067] The results are shown in Table 1 below:

[0068] Table 1 Performance test of facial mask substrate

[0069]

[0070] It can be seen from the data in Table 1 that the antimony-free high liquid holding rate nonwoven substrate obtained in the present invention does not use an antimony-containing catalyst in the preparation process, is biocompatible and non-toxic, and avoids the potential risk brought by a small amount of antimony (III) contained in ordinary polyester fibers to the human skin. In addition, the nonwoven substrate used to manufacture the facial mask in the present invention has excellent comprehensive performance, high mechanical properties, high liquid holding rate, and good water retention performance, and can keep most of the water from flowing out within 1 h; while having excellent liquid holding rate and water retention performance, it also has very high air permeability, ensuring that the facial mask user has a comfortable and breathable feeling.

Claims

1. A non-antimony high liquid holding rate nonwoven substrate, which is a three-layer composite structure, is characterized in that, The antimony-free nonwoven substrate with high liquid holding rate is obtained by carding hyperbranched modified polyester fiber, viscose fiber and natural cellulose fiber into a web and then strengthening and compounding by hydroentangling; the hyperbranched modified polyester fiber is prepared by a preparation method including the following steps: (S1) Under an inert atmosphere, trimethylolpropane, sorbitol, dimethylolpropionic acid and p-toluenesulfonic acid are fed in a molar ratio of 7-10:1-1.4:25-30:0.3-1, and the molar ratio of the carboxyl group in dimethylolpropionic acid to the hydroxyl groups in trimethylolpropane and sorbitol is 1.05-1.15:1; an esterification reaction is carried out to obtain a first-generation branched polyol; dimethylolpropionic acid and p-toluenesulfonic acid are added to the first-generation branched polyol, and the added amount of dimethylolpropionic acid is such that the molar ratio of the carboxyl group of dimethylolpropionic acid to the hydroxyl group of the branched polyol is 1-1.03:1, and the added amount of p-toluenesulfonic acid is 0.01-0.03 times the molar amount of dimethylolpropionic acid, and the esterification reaction is continued to obtain a second-generation branched polyol; the esterification reaction operation is repeatedly carried out to obtain a third-generation hyperbranched polyol or a fourth-generation hyperbranched polyol; (S2) Terephthalic acid and C2-5 diol are fed in a molar ratio of 1.05-1.14:1, and then 5-8 wt% of the third-generation or fourth-generation hyperbranched polyol prepared in step (S1) based on the mass of terephthalic acid is added. First, pre-polymerize at 210-230 °C and a pressure of 0.6-0.9 MPa for 1-2 h; then, 10-15 wt% of the third-generation or fourth-generation hyperbranched polyol prepared in step (S1) based on the mass of terephthalic acid and an organotin catalyst are added for polycondensation. The polycondensation reaction temperature is 250-270 °C, the pressure is 0.01-0.05 MPa, and the polycondensation is carried out until the acid value of the system is lower than 10 mg KOH / g, and the polycondensation time is 4-6 h; the added amount of the organotin catalyst is 1-2 wt% of the mass of terephthalic acid; Cool, filter, cast into strips, and pelletize to obtain polyester chips; (S3) The polyester chips, polyvinyl alcohol, lubricant, antibacterial agent, and antioxidant are fed into a twin-screw extruder in a mass ratio of 100:5-8:0.5-2:0.5-2:0-1, and extruded and pelletized; (S4) The masterbatch obtained in step (S3) is melt-spun, cooled, drawn, and wound to obtain hyperbranched modified polyester fiber; No antimony-containing catalyst is used in the preparation process of the hyperbranched modified polyester fiber.

2. The antimony-free high liquid holding rate nonwoven substrate according to claim 1, wherein The C2-5 diol is selected from at least one of ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, and neopentyl glycol.

3. The antimony-free high liquid-holding nonwoven substrate according to claim 1, wherein The natural cellulose fiber is selected from at least one of hemp fiber, cotton fiber, and bamboo pulp fiber; the dry strength of the viscose fiber is 35-50 cN / tex.

4. The antimony-free high liquid holding rate nonwoven substrate according to claim 1, characterized in that, The fineness of the hyperbranched modified polyester fiber is 1.0 - 1.2 dtex, and the surface density after carding of the hyperbranched modified polyester fiber is 10 - 15 g / m 2 ; The fineness of the natural cellulose fiber is 0.6 - 0.9 dtex, and the surface density after carding of the natural cellulose fiber is 20 - 30 g / m 2 ; The fineness of the viscose fiber is 1.2 - 1.4 dtex, and the surface density after carding of the viscose fiber is 10 - 15 g / m 2 .

5. The antimony-free high liquid holding rate nonwoven substrate according to claim 1, wherein Repeatedly carrying out the esterification reaction operation means that after obtaining the branched polyol, dimethylolpropionic acid and p-toluenesulfonic acid are continuously added for esterification reaction. The added amount of dimethylolpropionic acid is such that the molar ratio of the carboxyl group of dimethylolpropionic acid to the hydroxyl group of the branched polyol is 1-1.03:1, and the added amount of p-toluenesulfonic acid is 0.01-0.03 times the molar amount of dimethylolpropionic acid.

6. The antimony-free high liquid holding rate nonwoven substrate according to claim 1, wherein In step (S1), the conditions for the esterification reaction are to control the reaction temperature at 120 - 140 °C and react for 4 - 6 h; the post-treatment after the esterification reaction is to cool, perform rotary evaporation, dissolve the obtained product in acetone, add a non-polar solvent, precipitate, filter, and dry; the non-polar solvent is selected from at least one of n-hexane and petroleum ether; and / or In step (S2), the organotin catalyst is selected from at least one of dibutyltin dilaurate, tin oxalate, stannous octoate, and dibutyltin dioctoate.

7. The antimony-free high liquid holding rate nonwoven substrate according to claim 1, characterized in that, In step (S3), the number-average molecular weight of the polyvinyl alcohol is 1000 - 2000 g / mol; the lubricant is selected from pentaerythritol stearate and polyvinylpyrrolidone; the antibacterial agent is selected from at least one of silver nanoparticles and quaternary ammonium salts; the antioxidant is selected from at least one of BHT1010 and 2246; and / or In step (S4), the melt spinning process temperature is 300 - 320 °C, the setting temperature is 140 - 160 °C, the POY spinning speed is 2500 - 3000 m / min, the POY draw ratio is 1.5 - 2 times, the FDY spinning speed is 4000 - 4500 m / min, the FDY draw ratio is 3 - 3.5 times, and the winding speed is 2000 - 3000 r / min.

8. The preparation method of the antimony-free high liquid-holding nonwoven substrate according to any one of claims 1-7, characterized in that, It includes the following steps: Loosen the hyperbranched modified polyester fiber, viscose fiber, and natural cellulose fiber respectively, card them into webs, and sequentially laminate the hyperbranched modified polyester fiber web, viscose fiber web, and natural cellulose fiber web in order from top to bottom. After lamination, hydroentangle and dry, then crimp to obtain the antimony-free high liquid-holding nonwoven substrate.

9. The preparation method according to claim 8, characterized in that, Control the injection amount of each fiber to meet the requirement of areal density, that is, the areal density after carding of the hyperbranched modified polyester fiber is 10-15 g / m 2 ; the areal density after carding of the natural cellulose fiber is 20-30 g / m 2 ; the areal density after carding of the viscose fiber is 10-15 g / m 2 .

10. The preparation method according to claim 8, characterized in that, The lamination is at 30 - 60°; the hydroentangling process is that the distance of the water needle action is 10 - 20 mm; perform 3 - 5 passes of hydroentangling, the water pressure is 1.5 - 8 MPa, and the water pressure first rises and then falls.

11. According to the preparation method described in claim 8, characterized in that, Adopt a 4-pass hydroentangling process, the water pressure of the first pass of hydroentangling is 1.5 - 3 MPa, the water pressure of the second pass of hydroentangling is 3 - 6 MPa, the water pressure of the third pass of hydroentangling is 6 - 8 MPa, and the water pressure of the fourth pass of hydroentangling is 3 - 5 MPa.

12. A facial mask, comprising a facial mask substrate and a nutrient solution, characterized in that, The facial mask substrate is the antimony-free high liquid-holding nonwoven substrate according to any one of claims 1 - 7.

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